Glyphosate is the main active component in Roundup®, which is a product from Monsanto Co., Ltd. It is a kind of broad spectrum, translocated and excellent herbicide and it is one of the herbicides widely used. However, it is also a non-selective herbicide and it may kill the crop as well. It is desirable to breed a crop with glyphosate resistance or degradation property in order to use glyphosate in the agricultural production.
Glyphosate inhibits the activity of 5-enolpyruvylshikinate-3-phosphate synthase (EPSP) in the Metabolic process of shikimic acid, and thus blocks the biosynthesis of aromatic amino acids, which leads to the death of the plant (S. R. Padgette et al., in. Herbicide-Resistance Crops: Agricultural, Environmental, Economic, Regulatory, and Technical Aspects, S. O. Duke, Ed. (CRC Press; Boca Raton, Fla., 1996), pp. 53-84). Currently, all the transgenic plants with glyphosate resistance commercially grown in the world are designed in allusion to EPSP, which is the only mechanism of action of commercial transgenic plants with glyphosate resistance AroA mutants were obtained using chemical mutagenesis of bacteria, and it was confirmed that aroA gene was the encoding gene for EPSP synthase which is the action target of glyphosate through the study of mechanism of drug resistance. More than 100 patents in the field of encoding gene aroA for EPSP synthase and the transgenic plants with glyphosate resistance had been filed by many companies such as Monsanto and Calgene in USA, and a series of transgenic crops with glyphosate resistance had been obtained, such as soybean, corn, brassica, sweet beet and cotton, wherein many transgenic crops including soybean had been commercially produced.
Up to now, there is no report about EPSP synthase which has glyphosate resistance and lower homology with the reported encoding gene of EPSP synthase (aroA) at nucleotide level.